The present invention relates to a shock absorber for vehicles with pneumatic suspension, particularly for heavy vehicles, of the type comprising a cylinder, a rod movable axially in the cylinder, a piston carried by the rod and dividing the cylinder into a cylindrical chamber and an annular chamber, a pressurized fluid filling the cylindrical and annular chambers, a first circuit for allowing the fluid to flow from the annular chamber to the cylindrical chamber when the shock absorber is working under extension, a second circuit for allowing the fluid to flow from the cylindrical chamber to the annular chamber when the shock absorber is working under compression, a pressurized fluid reservoir connectable to the cylindrical and annular chambers and flow regulators mounted in the first and second circuits for controlling the flow of pressurized fluid therein. These flow regulators being controlled by the compressed air of the corresponding pneumatic suspension of the vehicle.
Heavy vehicles such as trucks, trailers and semi-trailers are called on to withstand loads which may vary in very wide proportions depending on whether they are used empty or with maximum load.
Most of them are equipped with pneumatic suspensions suitably fulfilling their function whatever the load transported, the pressure of the compressed air in the bellows or diaphragms of the suspensions being proportional to said load.
On the other hand, the shock absorbers of these different heavy vehicles have constant shock absorbing characteristics and can only correctly damp the oscillations of the suspensions for a given load.